Electronic mail (e-mail) is a well-known system for exchanging electronic messages. While the use of e-mail as a method of communication has rapidly increased, there are a number of phenomena that can limit the usefulness of e-mail.
One such phenomenon is spamming. Spamming is sending, in large quantities, unsolicited commercial e-mails. An e-mail recipient may receive a large number of “spam” e-mails, which can present a challenge to a user in discerning important e-mails from spam.
Another such phenomenon is e-mail bombing. E-mail bombing is sending a large volume of messages to a single e-mail address in an effort to render it unusable and/or cause the e-mail server to fail.
A third such phenomenon is transmitting viruses or worms via e-mail. Such viruses and worms can take malicious action on an unwitting recipient's computer and cause data loss, system unavailability, or other detriments.
In addition to the above-discussed phenomenon, e-mail also presents the risk that confidential information included in an e-mail message may be received by an unintended recipient. For example, when sending confidential information via e-mail, the sender may accidentally send the e-mail to the wrong person, such that someone who is not authorized to view the confidential information receives it. Moreover, when confidential information sent via e-mail is not encrypted, there is a risk that the confidential information may be maliciously intercepted by someone who is not authorized to have access to the information.